For other "decision values" that would be easier, but since your columns 1+2 hold time/date values, that won't work. There's simply no way you can inform gnuplot that columns 1 and 2 of your data file are time/date values in a particular format unless you actually use them in the plot.

I have two questions I was hoping someone could help me with. I've looked in the faq and the manual and didn't find these addressed.

First, is there a way to change the default page/plot dimenstions in gnuplot? I'd like to generate a plot for legal or 11x17 paper, or better yet, a plot to print on a large format plotter (several feet in width and arbitrary length).

Second, I've been amazed at gnuplots ability to plot large data sets. Unfortunately, I managed to kill it on a 3 month data file with 1 second samples. I assume this is largely due to an insufficient amount of ram on my machine and not some other limit in gnuplot. My question is simply, will a memory addition do the trick, or are there some hard limits to the number of data points gnuplot can plot? Or is there perhaps a better way to make a plot of this magnitude?